A social network service is a computer- or web-based application that enables users to establish links or connections with persons for the purpose of sharing information with one another. In general, a social network service enables people to memorialize or acknowledge the relationships that exist in their “offline” (i.e., real-world) lives by establishing a computer-based representation of these same relationships in the “online” world. With a social networking site or service, a user may have many options for sharing information with others. For example, a user may communicate a private message to a single user, for example, by directing an email to the user, or by posting the message to a web page only accessible to the recipient. In addition to sharing user-generated content, a social networking user may share information by sharing a link (e.g., a hyperlink or Uniform Resource Locator (URL)), directing the recipient to an external content source, such as a blog site, news site, or an audio or video clip of potential interest to the recipient. In addition to enabling one-to-one sharing, many social network services make it easy to share information with multiple users, including groups. For example, some social network services enable a user to post a message to, or share a link with, all users or some predefined set of users. With some social networks, users can self-organize into groups, such that like-minded individuals, or individuals with a common interest, can become members of the same group for purposes of sharing information and communicating with one another.
As users of social network services become more accustomed to interacting with and via the services, and as users become accustomed to sharing more personal information using the services, the services have access to greater amounts of more personal user information. Consequently, opportunities exist to improve and enrich the overall experience by presenting to users the right mix of information at the right time.